Yellow spots on my plant

Probably just some hot starting soil.. they were looking fine before. They will probably grow into it!

too many possibilities... 8 days old.. light burn would have been preceded by wilting -- so you can rule that out if it didn't fall over. have you been feeding? if so, don't. a seed is good for upto 2 weeks, plust your soil will have nutes (hydro is a bit different). when cotyledons fade you can feed.. if it is something like Ocean Fores (a hot soil), you likely won't feed for a month or more. so, no nutes, and when you irrigate, make sure the pH is ~6.5-6.8 -- a little sway is healthy, big sway is not. 6-7 is probably safe, for example, but a smaller range of volatility is better. get 100pack of strips for $5-7 that resolve down to 0.1pH. By the time you know how to pH your tap or tap+nutes mix, you won't have to do it repeatedly... just measure things out and it'll be your new recipe when mixing.

Pics for reference will help friend!